2 
mented family of insects. Within each of the tribes the diversity 
of forms is so great that it has become absolutely necessary to 
subdivide them, and ascertain at the same time the relations of 
the subdivisions to each other. I was therefore unwilling to 
publish descriptions of the new forms without first attempting 
to class the whole in natural groups, as well as to define better 
the already known genera. A mere succession of a multitude of 
genera treated in an isolated manner, without indications of the 
affinities which link them together (such, in fact, as has been 
given hitherto in works on the family), could lead to no useful 
scientific results. 
No general treatise has appeared on this subject (until within 
the last few months) since the imperfect one of Audinet-Serville 
in 1832-4. In this work the genera are very insufficiently charac- 
terized, often from the examination of a single species. Shortly 
afterw^ards appeared the third edition of the Catalogue of Count 
Dejean, in which a great number of new genera were introduced 
without characters at all. On the uncertain foundation, how- 
ever, of these two works, a vast number of new species and ge- 
nera have been published, many of the former being referred, in 
a most loose and unsatisfactory manner, to the uncharacterized 
genera of Dejean. The want of a good monograph, such as 
exists on many other families of Coleoptera, has long been felt. 
Faunists, in treating of the family in their special works, and 
authors of the numerous works on the zoology of voyages, public 
and private, have been obliged to describe great numbers of new 
genera and species without reference to a reliable general classi- 
fication ; besides which, many Coleopterists to whom the family 
is attractive on account of the great beauty and variety of its 
forms, have continually published isolated descriptions of new 
species and genera, and this in every variety of natural-history 
periodical, and in almost every European language. In this 
w^ay at length about 820 genera and 4500 species have been in- 
troduced into the science, a very large portion of them without 
proper indications of their place in the system. 
The general treatise upon the Longicornes which I have 
alluded to above as having appeared very lately is by M. J. 
Thomson of Paris, and entitled ^Essai dffine Classification de la 
Familie des Cerambycides.^ It is founded on a previous special 
work on the North American Longicornes published by Dr. Le- 
conte in 1852, called ^ An Attempt to classify the Longicorn 
Coleoptera of America north of Mexico.^ The latter essay was a 
great step in advance, as it entirely remodelled the previous 
knowledge on the subject, and took into account many parts of 
the structure of these insects which were left unheeded by pre- 
